Global specialty plastics provider Eastman (Kingsport, TN) makes it the company’s business to work with product developers to help the industry evolve in various markets. It recently collaborated with DW Designs to mold and test beryllium models in ear monitor housings using a variety of materials. Eastman’s John Quigley and DW Designs’ Dan Wiggins presented their findings at the annual Rocky Mountain International Audio Fest (CanJam) held in Denver in October.
Audiophiles love purity of sound, and delivering that experience in electronic entertainment systems was the goal of Eastman and DW Designs (Port Hueneme, CA). According to Eastman’s Alex Dudal, audio is crucial to the success of smart entertainment such as streaming services, smartphones and other devices in providing high-quality content.
“Audio apps are a huge driver of this industry and previously Eastman has looked at how our materials impact the quality of audio,” Dudal told PlasticsToday. “We want a better understanding of the properties of our materials and how to help in delivering high-quality audio.”
Quigley, Senior Application Development Engineer for Eastman, said, “We worked with DW Designs to test housings molded in an incumbent polycarbonate material, as well as Eastman’s copolyester and cellulosic resins to understand how these materials might improve acoustic performance in audio applications.”
Various materials have a distinct acoustic performance. Using Eastman’s materials for the ear monitor housings, Eastman and DW tested each of the polymers for both cumulative spectral decay and total harmonic distortion. “The enclosure (or housing) has natural resonances that affect the user’s experience,” explained Quigley. “What we’re trying to do is limit that contribution to the listener. The results were measurable and audible improvements in the in-ear monitors molded with Tritan and Treva."
Data indicated the Tritan copolyester outperformed the polycarbonate, while the Treva cellulosic (plant-based) resin offered superior results, both in terms of clean response and lower distortion. Specifically, the polycarbonate had the most peaks for resonance whereas cellulosic had the lowest resonance and contribution to total harmonic distortion.
Eastman’s cellulosic material, Treva, is sourced from sustainably managed forests, explained Quigley. The goal of this work, added Quigley, is to suppress any vibration or resonance created by the housing to allow the electronic device to accurately reproduce the intended sound from the transducer and not contribute its own sound.
What is the fundamental reason for the improved performance? That is something Eastman is still trying to understand. “How can we provide more value to the market? How does Eastman’s material improve the audio performance to the consumer? Is it in the visco-elastic response, and why is it unique to the Treva cellulosic and Tritan copolyester materials? We’re trying to understand that on a fundamental level,” said Quigley.
DW Design consultant Dan Wiggins commented that “Eastman polymers have shown, through my own independent testing and experimentation, to provide measurable and audible improvements in many products that utilize plastics. Easy to mold, durable, incredibly high internal energy dissipation and affordability make products like Tritan and Treva a no-brainer for many consumer audio products. They are now my ‘go-to’ recommendation for molded acoustic enclosures.”
Listener feedback demonstrated that consumers were able to hear fine details better and preferred the acoustic performance of enclosures made with Tritan and Treva.
“If you look beyond plastics and consumer interest,” said Dudal, “macro trends show an interest in ingredients and what things are made of. Having a unique material that creates benefits that no other manufacturer can provide will result in better demand.”